Arctic Archipelago

Glaciers and ice caps are common in the Arctic Archipelago Ecozone and trap the majority of the freshwater, rendering it unusable to plants and animals. There are many small lakes, but since they remain frozen for 9 or 10 months of the year, plant and wildlife populations are limited. Species that are able to survive in these lakes are very hardy. Despite the harsh winter temperatures and frozen habitat, spring in this ecozone brings a rush of meltwater and nutrients, encouraging growth. Numerous species of wetland plants, such as mosses, thrive in the ephemeral wetlands that are formed with the spring melt.

Climate has profound effects on the quantity of freshwater in this ecozone. Lakes and streams are fed by melting ice caps and glaciers, and so release little discharge in the winter, but flow increases greatly as temperatures rise in the spring. Rivers and wetlands have their highest water levels in July, when meltwater is at its peak, and are often completely dried up by September. Water flow in streams and rivers varies day to day, or even hour to hour, as the sun's radiation increases in intensity. Vegetation and wildlife must be adapted to their constantly changing habitat to ensure successful reproduction and survival.

Freshwater in the Arctic Archipelago Ecozone is found in glaciers, ice caps, streams, lakes, and wetlands. Water in lakes and streams fed by glacial meltwater is cloudy, due to the large amounts of sediment – sand, silt, and clay – that is released with the meltwater. There are two main lakes in this area that provide important habitat for numerous invertebrates and a few fishes. Lake Hazen is the world's largest lake entirely north of the Arctic Circle. It is located in the Eureka Uplands on Ellesmere Island and is underlain by Precambrian rock. Lake Hazen remains constantly ice covered, except in very mild years. By contrast, the second major lake, Lake Nettilling, thaws yearly. Located on southern Baffin Island and bisected by the Arctic Circle, Lake Nettilling is the largest lake in the Archipelago and the tenth largest lake in Canada. These lakes, and the rivers which link them to the Arctic Ocean, are home to a variety of freshwater plant and animal species.

Freshwater vegetation is limited throughout the Arctic Archipelago. Most lakes have little vegetation except algae, which bloom when the ice thins, and mosses which line their bottoms. The algae are able to develop quickly in the short growing season and avoid freezing by reducing the amount of free water in their cells. The benthic mosses are slow growing and, like the algae, can survive with ice cover. All of the fish and invertebrates that occur here depend on these plants for their survival. In mild years, when the productivity of vegetation increases, there is a direct increase in wildlife productivity.

Few organisms can survive arctic waters and ice cover for 10 months of the year, and so many of the large-sized species that occur here, such as swans and Canada geese, are migratory. In Lake Hazen, only a small population of arctic charr inhabits the icy water, but Lake Nettilling supports arctic charr, threespine sticklebacks, and ninespine sticklebacks.

Fish in the Arctic swim more slowly than their temperate zone relatives because of the cold temperatures. A variety of invertebrates, especially copepods, inhabit the freshwaters and provide food for fish and larger wildlife species. Many of the invertebrates enter a dormant state in the winter to survive the ice cover. Others cannot survive, but instead lay eggs that can withstand freezing and then hatch the following spring. In the wetlands of the Arctic Archipelago, migratory birds, such as snow geese, eider, and red-throated loon find suitable habitat.